So what happens is im playing and without a warning screen turns black and it pops up at the desktop. The game still goes on, i still have audio but i dont have any video. I think its my video card its a gtx 670 i got a month ago. This happens every few days all on the same game but its not the most intensive(wargame:european escalation). I did do some overclocking is this behavior symtoms of lack of voltage?

Another issue i have is in some games like planetside 2 it will freeze for a second or two come back and i will be getting 20 fps when i normally get 60 and doesnt fix itself until i restart the game.